Grinding-mill



uNiTEO STATES 'PATENT OFFICE.

CARL G. THOMPSO, OF KNOXVILLE, TENNESSEE.

GRINDING-MILL.

Specification of Letters Patent.

Patented Oct.v 4, 1921.

Application led October 30, 1920. Serial No. 420,666.

To all whom t may concern.

Be it known that I, CARL G. THOMPSON,

a citizen of the United States, residing at Knoxville, in the county of Knox and State of Tennessee, have invented certain new andk re-grinding bran andother similar lmaterial,

' clogged.

such as flour containing bran. The flaky nature of bran necessitates the employment of feed passages of relatively large area'and means for forcing the material under pressure in a continuous stream through the said passages, Otherwise the mill will become The grinding heads must eachbe revolved in the `saine direction, but at different 'speeds, and must be free'to slide a little Vawa-y from each other to permit any lumps to pass from between them.

In the drawings, Figure 1 is a front view, partially in section, of the principal parts of a grinding mill constructed according to this invention- Fig. 2 is an end view of the grinding heads, the upper one-half of the high speed head being omitted to show the grinding plates of the low speed head.' Fig. 3 is a diagrammatic plan View of portions of the grinding heads and plates, partiallyin section on the line 3-3 in Fig. 2. Fig. 4 is a longitudinal section through the inlet end portion of the feeding device.

Two grinding heads 6 and 7 are provided, and arranged inside a suitable casing 3 having an outlet 9 for the ground material at its lower part. The casing is secured on a suitable base 10, to which also are secured shaft bearings 12, 14- and 15 of approved construction. The high speed grinding Ahead 6v is secured on a shaft 16 which is journaled in the bearing. 12, and provided with a. driving pulley 17. The shaft 16 has also another bearing, and means for adjust- V ing the shaft longitudinally, but these parts are not shown as they are of any approved construction.

The low speed grinding head 7 is secured on a tubular shaft 18 which is journaled in Vthem as found most desirable.

the bearingslst and 15, and provided with ra pulley 19 for revolving it. The tubular shaft 18 also serves as a feed passage for introducing the materia to be ground bctween the grinding plates of the grinding heads.

The grinding heads are both revolved in the same direction.l as indicated by the arrows in Figs. 2 and 3, the high speed head 6 having double arrows adjacent toit to indicate that it is driven at a` greater speed than the head 7. The speedsare arranged and proportioned sov as to give the best results from the differential action.

The grinding plates are secured to the respective heads by any suitable fastening devices,v such as the screws 20. rThe grinding plates of the high-speed head 6 prefer'- ably comprise "an inner ring 21, and a series of segmental'plates 22 arranged around the inner yring in circular form. The inner ring 21 has a series of teeth 23 cut in its face by any suitable machine. These teeth are shapedV like saw teeth in cross-section, and n are arranged with their edges foremost in the direction of motion. These teeth 23 are arranged diagonally, and their inner end portions are arranged rsubstantially atV a tangent to the periphery ofthe driving shaft 16, with their inner Vend portions. in advance of their outer end portionsin the direction of motion.

The Outer plates 22 are each provided with furrows 25, and grooved or corrugated faces 26 arranged alternatelyv of the furrows. The furrows 25 are triangular in `cross-section, and their ends 27 are arranged rearniost and are slightly undercut. These furrows may be cut in the plates or cast in The faces 26 and the furrows 25 are also arranged diagonally,'or at a tangent to the shaft 1.6, similarto the teeth 23, and the line diagonal co-rrugations are macliine'cut. The faces`26 have their teeth or corrugations cut in them with a machine, and arranged tangentially of the shaft 16 of the grindinghead. These corrugations may be rounded or they may be teeth similar to the teeth 23 in form Or cross-section, or they may be of other suitable form.

The grinding plates of the low speed head 7 preferably comprise an inner ring 31, and a series of segmental plates 32 similar to head. The inner ring 31 has machine cut radially of the axis of the grinding head.V

As the opposedteeth 23 and 33 are arranged diagonally of each other and run pointvto" point, their cutting edges have a slicing action on the material or grain which is fed between them. The teeth are made like saw teeth in cross-section sothat they will retain their sharp cutting edges as'the plates become worn away. rlhe segmental plates 32 are provided with radial furrows 35 and radially grooved or corrugated faces 36, similar to the furrows 25 and faces 26 Vof the plates 24:. The ends 37 Vof the furrows 35 are however arranged foremost in the direction of motion, so that they are overtaken by the ends 27, and the material or grain is operated on by the cutting edges of the said ends 27 and 37. v y

By using machine cut teeth and corrugations `as hereinbefore described, and by revolving the grinding heads at differential speed in the same direction, the material or grain can be ground very fine. V'lhe grindingheads do not have to be revolved so fast vas in the millsV ordinarily constructed, and

v less power is required to revolve the grinding heads.

r[he material or grain is fed through the tubular shaft 18 from a hopper 40 by means of a spiral conveyer 4l. The hopper 4() has a conical chamber 42 at its lower part, which is secured to the bearing 15 or other stationary part of the mill. The conical chamber 42 is arranged in line with the tubular shaft, and the conveyer shaft has Y a conical end portion 43 which is arranged in the conical chamber 42 and provided with conveyer flights 44. The conveyer is re' volved by any approved means, such as the wheel45. rlhe conical part 43 and the conveyer flights on it operate as a force feeder and pack the material into the tubular shaft and prevent it from revolving with the spiral conveyer withoutibeing moved longitudinally. p

Instead of providing'the conveyer with a driving wheel 45, its shaft can be connected with the shaft'lG of the high speed grind@ ing head by a screwthreaded portion't, or other suitable coupling. Y

The bran, or other similar material is forced between the inner rings of the grinding heads, and the slicing action -of the teeth reduces it to a preparatory fineness. The material is then forced under pressure aided by centrifugal action into Ythe furrows of the outer plates,`and the; grinding is completed by the line corrugations, the

furrows and fine corrugations of the'high speed head being arranged'diagonally of they radial furrowsv and corrugations ofthe low speed head, and also operating with .a slicing action upon the material.

lVhat I claim is: I .Y

In a mill fiorire-grinding bran and other similar material, Atwo horizontal V'driving shafts arranged end to end,one' of the said shafts being tubular, means forfirevolving they said shafts at different speeds inthe same direction, vopposed vertical grinding heads secured onV thev said shafts, me

tallicinner grinding rings secured to theY said heads andV provided. with relatively coarse` saw-shaped grindingteeth which work point to point, metallic outer grindingV rings encircling the inner grinding rings and providedv with feed furrows and finely y CARLV e. TrioMPsoN i 

